PROJET SUMMARY Increased utilization of prescription opioids for pain management has led to a nationwide public health crisis. In surgical settings, poorly coordinated pain management causes excessive opioid prescribing after surgery, which promulgates a gateway for opioid diversion, misuse, and dependency. Patients on chronic opioids before surgery present a special risk because they require higher opioid doses after surgery to achieve adequate pain control. However, few evidence-based approaches are available for managing pain in patients on chronic opioid therapy, particularly for those with postoperative pain. To address this gap, we developed a Perioperative Pain Program (PPP) to coordinate the continuum of care for surgical patients on chronic opioid therapy throughout the perioperative period. A multidisciplinary team, which included acute and chronic pain specialists and psychiatrists with expertise in addiction medicine, partnered with patients through preoperative consultation, postoperative inpatient hospitalization, and postoperative outpatient follow-up to develop personalized multimodal pain management plans and treat underlying psychiatric, behavioral, and psychological comorbidities. In the proposed project, we will evaluate the implementation and effectiveness of the PPP. To evaluate the implementation, we will apply a mixed methods approach with a convergent parallel design. Both quantitative and qualitative data will be collected and triangulated using different methods (chart reviews, observations, interviews). To evaluate the effectiveness, we will apply a quasi-experimental interrupted time series design comparing opioid prescription and patient self-reported outcomes (e.g., pain, functionality) between patients participating in PPP and a control group. In addition, we will adapt an educational program to improve patient engagement in the PPP. A pragmatic randomized trial will be done to assess the impact of the adapted program on patient engagement, opioid prescription, and other patient self- reported outcomes. This project focuses on prescription opioid use in perioperative pain management, which is a critical public health problem with significant consequences and costs. It will provides empirical evidence on the effectiveness of the PPP in preventing the overuse of prescription opioids and improving outcomes of surgical patients, which can inform future efforts to improve medication use and safety.